Explanations for Forgetting: Interference

• Interference theory

  - Occurs when two pieces of information disrupt each other, resulting in forgetting of one or both, or distortion of the memories.

  - Interference has been proposed as a form of forgetting in LTM mainly. Once information has reached LTM, it is essentially permanent, so any forgetting of LTMs is most likely because we can't access them, despite being available.

  - Interference between memories make it harder to locate them - this is forgetting.
• Define 'proactive interference'

  PI occurs when an older memory interferes with a newer memory.
• Define 'retroactive interference'

  RI happens when a newer memory interferes with an older memory.
• McGeoch and McDonald (1931): Research on the effects of similarity

  - Procedure: McGeoch and McDonald investigated RI by altering similarity between two materials. Participants had to learn a lit of 10 words until they could remember with 100% accuracy. They then leaned a new list.

  
  

  - Participants were split into six groups each receiving a different lit:

  - List 1: synonyms

  - List 2: antonyms

  - List 3: words unrelated to first list.

  - List 4: consonant syllables

  - List 5: 3 digit numbers

  - List 6: no new list, participants just rested (control)

  
  

  - Findings: When participants were asked to remember the original list, the most similar material, i.e. synonyms, produced the worst recall.

  - McGeoch and McDonald's (1931) research shows that interference is strongest with similar memories.
• Evaluating interference theory: Real-world interference (with counterpoint)


  - A strength is that there is evidence supporting interference affecting memory in real-world situations.

  - Baddeley and Hitch (1977) asked rugby players to recall which teams they had played against in the last season.

  - The players all played for the same time interval, but some were missed due to injuries for example.

  - Players who played the most games had the weakest recall (strongest interference).

  - This shows that interference occurs in at least some everyday situations.

  
  

  - Counterpoint: Interference may cause some forgetting but the conditions necessary for interference are rare.

  - This contrasts to lab studies where there is a high degree of control, so researchers can create ideal conditions for interference.

  - This suggests that most forgetting may be better explained by theories such as retrieval failure due to a lack of cues.
• Evaluating interference theory: Interference and cues

  - A limitation is that interference is temporary, and can be easily overcome through cues.

  - Tulving and Psotka (1971) gave participants lists of words organised into categories (participants didn't know the categories).

  - Recall averaged around 70% on the first list and this reduced as each list as given (PI).

  - At the end of the procedure, the participants were given a cued-recall test, and were told the name of the categories. Recall rose to the original 70%.

  - This shows that interference causes a temporary loss of access to LTM, a finding not predicted by the interference theory.
• Evaluating interference theory: Support from drug studies

  - Another strength is evidence of retrograde facilitation.

  - Coenes and van Luijtelaar (1997) gave participants a list of words and asked them to recall the list. They assumed that experiences between learning and recall would act as interference.

  - When a list of words was learnt under the drug diazepam, recall a week later was poor compared to a placebo control group.

  - However, when the list was learned before taking the drug, recall was better than the control group. The drug facilitated recall of previous material learned.

  - Wixted (2004) suggests that drug prevent new information entering the memory system, so it cannot retroactively interfere with information already stored.

  - The two studies show that interference causes forgetting; if you reduce the interference, you reduce the forgetting.
• Evaluating interference theory: Validity issues

  - Most studies supporting interference were lab-based, leading to control over confounding variables.

  - This provides a clear link between interference and forgetting. However, interference studies use artificial stimuli and unrealistic procedures, meaning that they lack external validity.